[DB] Alembic: factorize ReversibleOp

gargantext/util/alembic.py

@@ -7,6 +7,8 @@ the name of "ReplaceableObject" class.
 This recipe is directly borrowed from Alembic documentation, see
 http://alembic.zzzcomputing.com/en/latest/cookbook.html#replaceable-objects
 
+**2017-10-09** ReversibleOp.define has been added to reduce boilerplate code.
+
 """
 
 from alembic.operations import Operations, MigrateOperation
@@ -58,57 +60,32 @@ class ReversibleOp(MigrateOperation):
         operations.invoke(drop_old)
         operations.invoke(create_new)
 
+    @classmethod
+    def define(cls, name, cname=None, register=Operations.register_operation):
+        def create(self):
+            return CreateOp(self.target)
 
-@Operations.register_operation("create_view", "invoke_for_target")
-@Operations.register_operation("replace_view", "replace")
-class CreateViewOp(ReversibleOp):
-    def reverse(self):
-        return DropViewOp(self.target)
-
-
-@Operations.register_operation("drop_view", "invoke_for_target")
-class DropViewOp(ReversibleOp):
-    def reverse(self):
-        return CreateViewOp(self.target)
-
-
-@Operations.register_operation("create_sp", "invoke_for_target")
-@Operations.register_operation("replace_sp", "replace")
-class CreateSPOp(ReversibleOp):
-    def reverse(self):
-        return DropSPOp(self.target)
-
-
-@Operations.register_operation("drop_sp", "invoke_for_target")
-class DropSPOp(ReversibleOp):
-    def reverse(self):
-        return CreateSPOp(self.target)
-
+        def drop(self):
+            return DropOp(self.target)
 
-@Operations.register_operation("create_trigger", "invoke_for_target")
-@Operations.register_operation("replace_trigger", "replace")
-class CreateTriggerOp(ReversibleOp):
-    def reverse(self):
-        return DropTriggerOp(self.target)
+        name = name.lower()
+        cname = cname or name.capitalize()
 
+        CreateOp = type('Create%sOp' % cname, (ReversibleOp,), {'reverse': drop})
+        DropOp = type('Drop%sOp' % cname, (ReversibleOp,), {'reverse': create})
 
-@Operations.register_operation("drop_trigger", "invoke_for_target")
-class DropTriggerOp(ReversibleOp):
-    def reverse(self):
-        return CreateTriggerOp(self.target)
+        CreateOp = register('create_' + name, 'invoke_for_target')(CreateOp)
+        CreateOp = register('replace_' + name, 'replace')(CreateOp)
 
+        DropOp = register('drop_' + name, 'invoke_for_target')(DropOp)
 
-@Operations.register_operation("create_role", "invoke_for_target")
-@Operations.register_operation("replace_sp", "replace")
-class CreateRoleOp(ReversibleOp):
-    def reverse(self):
-        return DropRoleOp(self.target)
+        return (CreateOp, DropOp)
 
 
-@Operations.register_operation("drop_role", "invoke_for_target")
-class DropRoleOp(ReversibleOp):
-    def reverse(self):
-        return CreateRoleOp(self.target)
+CreateViewOp,    DropViewOp    = ReversibleOp.define('view')
+CreateRoleOp,    DropRoleOp    = ReversibleOp.define('role')
+CreateSPOp,      DropSPOp      = ReversibleOp.define('sp', 'SP')
+CreateTriggerOp, DropTriggerOp = ReversibleOp.define('trigger')
 
 
 @Operations.implementation_for(CreateViewOp)